A network router receives two identical candidate routes to destination network : one route was learned via OSPF (default administrative distance of ) and the other route was learned via RIP (default administrative distance of ). Assuming default protocol configurations are used, which route will the router install into its active routing table?
- The OSPF route, because it has a lower administrative distance value than RIPAnswer
- BThe RIP route, because distance-vector protocols bypass administrative distance checks at Layer 2
- CThe RIP route, because lower numerical administrative distance values indicate lower protocol preference
- DThe OSPF route, because OSPF automatically applies Port Address Translation (PAT) to override hop counts
Answer
The OSPF route will be installed into the routing table because its default administrative distance of 110 is lower and therefore more trustworthy than RIP's default administrative distance of 120.
When a router receives multiple paths to the exact same destination network prefix from different routing protocols, it compares their Administrative Distance (AD). AD represents the trustworthiness of the source. Lower AD values are preferred over higher AD values. Because OSPF has a default AD of 110 and RIP has a default AD of 120, the router selects the OSPF route for installation into the routing table.
Step-by-Step Solution
Key Concept
Administrative Distance Precedence in Route Selection